Android RecyclerView 瀑布流滑動到最後自動加載更多

mRecycleView.setOnScrollListener(new RecyclerView.OnScrollListener(){
    //用來標記是否正在向最後一個滑動，既是否向下滑動
    boolean isSlidingToLast = false;
 
    @Override
    public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
        StaggeredGridLayoutManager manager = (StaggeredGridLayoutManager) recyclerView.getLayoutManager();
        // 當不滾動時
        if (newState == RecyclerView.SCROLL_STATE_IDLE) {
            //獲取最後一個徹底顯示的ItemPosition
            int[] lastVisiblePositions = manager.findLastVisibleItemPositions(new int[manager.getSpanCount()]);
            int lastVisiblePos = getMaxElem(lastVisiblePositions);
            int totalItemCount = manager.getItemCount();
 
            // 判斷是否滾動到底部
            if (lastVisiblePos == (totalItemCount -1) && isSlidingToLast) {
                //加載更多功能的代碼
                Ln.e("howes right="+manager.findLastCompletelyVisibleItemPosition());
                Toast.makeText(getActivityContext(),"加載更多",0).show();
            }
        }
    }
 
    @Override
    public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
        super.onScrolled(recyclerView, dx, dy);
        //dx用來判斷橫向滑動方向，dy用來判斷縱向滑動方向
        if(dy > 0){
            //大於0表示，正在向下滾動
            isSlidingToLast = true;
        }else{
            //小於等於0 表示中止或向上滾動
            isSlidingToLast = false;
        }
 
    }
});

private int getMaxElem(int[] arr) {
        int size = arr.length;
        int maxVal = Integer.MIN_VALUE;
        for (int i = 0; i < size; i++) {
            if (arr[i]>maxVal)
                maxVal = arr[i];
        }
        return maxVal;
}